Grease wherein the thickener comprises metal soaps of hydroxy fatty acid formals



GREASE WEEREIN THE TEHEENER CONERISE METAL SOAPS 9F HYDROXY FATTY ACIDFCBRMALS Alfred H. Matuszalr, Westfield, Arnold J. Morway, Clark, andJohn C. Monday, Cranford, N. 3., assignors to Esso Research andEngineering Company, a corporation of Delaware No Drawing. ApplicationJune 15, 1954 Serial No. 437,009

9 Claims. (Cl- 252-39) This invention relates to lubricating greasecompositions. Particularly, the invention relates to lubricating greasecompositions prepared by thickening a lubricating oil to a greaseconsistency with metallic soaps of formals of hydroxy fatty acids. Theproducts are excellent grease compositions having outstanding structuralstability and long lubricating life.

There have recently become available new hydroxy fatty acids producedfrom unsaturated fatty acids by treatment with oxidation agents. Forexample, unsaturated acids having from about 14 to about 22 carbon atomssuch as tetradecenoic acids, e. g., myristoleic acid, tsuzuic acid,hexadecenoic acids, e. g., palmitoleic acid, octadecenoic acids, e. g.,petroselenic acid, oleic acid, elaidic acid, vaccenic acid, eicosenoicacids, e. g., gadoleic acid, docosenoic acids, e. g., erucic acid,cetoleic acid, mixtures of the above; and thelike; are oxidized withperacetic acid, resulting inpolyhydroxy acids such as di-hydroxy stearicacid, etc. These new hydroxy fatty acids are considerably less expensivethan the hydroxy fatty acids available heretofore, which have ordinarilybeen formed by the hydrogenation of castor oil. Naturally occurringhydroxy fatty acids, and mixtures, such as ricinoleic acid, 12 hydroxystearic acid, sabi'nic acid (l2-hydroxy lauric acid), juniperic acid (16hydroxy palmitic acid) are also available commercially.

It has now been found that greases of excellent properties can beprepared using derivatives of these hydroxy fatty acids in theformulation. In these modifications, the monoand polyhydroxy fatty acidsare reacted with formaldehyde to form (1) the simple di-acid formal fromthe monohydn'c acid, (2) the cyclic formal in the case of a dihydroxyfatty acid and (3) the hydroxy cyclic formal in the case of a trihydroxyacid.

These reactions of formaldehyde with mono-, diand tn'hydroxy acids areshown graphically asfollows:

OH:(CH2),(3H(EH-CH(CH2),OOOH ECHO OH O-CHz-O CHACHahGH-GH CH(CH2),,COOHH O (Hydroxy cyclic formal) ice 2. In addition to the above, mixedproducts could be formed. For example, the dihydroxy fatty acid couldreact with formaldehyde to form dihydroxy di-acidformals such as whilethe trihydroxy fatty acid could react with formaldehyde to form formalscontaining free hydroxy groups and/ or cyclic formal groups such asEXAMPLE I.SIMPLE SOAP GREASE USING A POLYHYDRIC FATTY ACID ALONEFormulation Polyhydroxy stearic acid 12.00 Lithium monohydrate 1.72Phenyl alpha-naphthylamine 0.50 Mineral oil 85.78

Preparation Charged mineral oil and acid to a fire heated grease kettleand warmed to 150 P. Then added the LiOH H2O as a 20% aqueous solutionand heated to 400 F. Added phenyl alpha-naphthylamine and allowed tocool; when cold, homogenized.

Penetrations, 77 F., mm./ 10:

Unworked 290.

Worked 60 strokes 350. Worked 100,000 strokes Fluidized.

No further work, due to poor structural stability of grease.

EXAMPLE IL-FORMAL OEPOLYHYDROXY ACID IN SIMPLE SOAP GREASE Thepolyhydroxy acid used to prepare the formal of this example was obtainedby the peroxidation of oleic acid. The polyhydroxy fatty acid had thefollowing physical and chemical properties:

Gardner color l6 Volatile matter percent 0.7 Melting point C 60-64 Acidvalue 170' Iodine value 4 Sap. value 181 Hydroxyl value 270 Formulationand preparation 7 Same as above, employing CHa(CHz)=CH-CH w 7 H 'fCHPPenetration (77 F.--mm./l0):

Unworked 255 Worked 60 str g 265 Worked 10,000 strokes 285 EXAMPLEIII.FORMAL MONOHYDROXY FATTY ACID IN A ,COMPLEX GREASE Charged'formal,hydrated lime and mineral oil to a fire heated kettle and warmed to 150F. Then added acetic acid and continued heating to- 500 F. Discontinuedheating and cooled .to 250-F. Added phenyl alpha-naphthylamine andcooled further to 200 F. Gaulin homogenized the product at 3000 p. s. i.pressure,

filtered and packaged.

XAMPLE IV v Formulation.

I Percent weight Formal of mono hydroxy stearic acid 2.0 Hydrofol acid51 2.0 Glacial acetic acid 8.0 Hydrated lime 6.0 Phenylalpha-naphthylamine 0.5

' Mineral oil (55 SUS/210 F.) 81.5

H 7 Preparation Similar to Example I.

Properties Example III ExampleIV Appearance Frnellrmt Excellent,Penetrations (7 7 F. min/10): I

' Unworked 256 250.

Worked, 60 stroke 330 271.

Worked, 100,000 strokes Semi-fluid... 368. Dropping point, F one None.Phase changes (70500 F.) do Do. wlleez bf [aring test 6 hours at 220 F.,660 Pass Pass. Ngrma-Hoiiman oxidation, hours to'5 p. st. 302 302.

rop. Water solubility (boiling water) None None.

EXAMPLE V.--FORMAL OF DI-HYDRQXY STEARIC ACLD IN COMPLEX GREASE Thedi-hydroxy stearic acid used in this-example had cc.). This materialconsisting of a mixture of simple and the following properties: Gardnercolor a a 10 Volatile matter (percent) 0.8 Melting point, C -83 Acidvalue 168 Iodine value 3 Sap. value 182 Hydroxyl value 257 r The hydroxystearic acid g., 0.3 m.) was heated During this time 6.2 cc.- of waterwas azeotroped from the reaction mixture (theory is about 6 cc.). Thematerial was then cooled, filtered to remove the catalyst and strippedto remove theheptane 1'20 The mineral oil, lime and high molecularweight acids were charged me fire heated kettle and warmed to 135 F. Theacetic acid was added andheating continued to 500 F. Shut 0E heat andwhile continuing to agitate,

cooled to 250 F. when the phenyl alpha-naphthylamine was added. Cooledto 200 F., then hon1'0genized,,filtered and packaged.

Properties: 7 7

Appearance Excellent, 5 h o r t fibre grease. Dropping point, "F None.Penetrations 77 F. mm./ 10: Unworked 210. Worked 60 strokes 265.

Worked 100,000 strokes 205 F.), 277 a f t e r cooling a n d workingadditional 60 strokes. Water solubility Nil.

Norma-Hoffman oxidation, hours to 5 p. s. i. drop in oxyge pressure;Wheel bearing test (6 hours at 250 F.) Pass, no leakage. Phase changesNone, up to 450 EXAMPLE VI.--FORMAL= OF .POLYHYDROXY STEARIC ACID INCOMPLEX GREASE Polyhydroxy 'stearic acid, 165.5 g. (0.5 m.), wasformalized with 8.2 g. parafo'rmaldehyde in the presence of 0.5 NaHSOcatalyst and 100 g. heptane for 2 hours at 107 C. The water collectedwas 7.4 cc. (theory is 9 cyclic formals was-filtered while hot and thenstripped free of heptane C. at 15 mm.). It had some free hydroxyl groupsstill remaining and was a mushy material which on standing solidified.It was used to prepare a grease as follows.

Formulation Ingredients: Percent weight Hydrogenated fish oil acids 2.0Polyhydroxystearic acid mono formal 2.0 Glacial acetic acid 8.0 Hydratedlime 6.0 Phenyl alpha-naphthylamine 0.5 Mineral oil (55 SSU/210 F.) 81.5

Preparation 5 Same as Example V.

Properties:

Appearance Excellent, smooth homogeneous product. Dropping point, "FNone. Penetration 77 F. mm./l0:

Unworked 210. Worked 60 strokes 228. Worked 100,000 strokes; 316. Watersolubility Insoluble.

Phase changes None up to 450 F. Wheel bearing test, 6 hours at 220 FPass, no leakage. Norma-Hoffman oxidation,

hours to 5 p. s. i. drop 375.

Lubrication life hours,

10,000 R. P. M.250 F- 1166.

It will be seen by the data in the examples above that the formals ofhydroxy fatty acids make excellent grease soaps, giving lubricatinggrease compositions having very satisfactory performancecharacteristics. As is shown in Example I, the polyhydroxy acids alonedo not form satisfactory grease compositions in that they tend tooverplasticize the grease and give products that are too soft to performsatisfactory lubricating functions.

In addition to the metals used in the example above, the formals of thehydroxy fatty acids may be saponified with any of the commonly knownalkali or alkaline earth metals to form satisfactory grease soaps. Thechoice of the metal component depends to a certain extent on the use forwhich the soap is contemplated. The alkaline earth metals, particularlycalcium, strontium, barium and magnesium, may be used and the alkalimetals such as sodium, lithium and potassium may also be used in certainformulations. The alkaline earth metals are particularly advantageousfor use in preparing the high acetate complex grease structures. As ispointed out above, in addition to the formal of the hydroxy fatty acids,other soap forming acidic materials may be incorporated into the greasecompositions of invention. Any of the commonly known high molecularweight acids having from about 12 to about 30 carbon atoms, preferablythose having from 14 to 22 carbon atoms, may be used. These acids may bederived from saturated or unsaturated, naturally occurring or syntheticfatty materials. Examples of operable fatty acids in clude stearic,arachidic, hydrogenated fish oil acids, coconut oil acids, tallow acids,etc.

When it is desired to prepare a complex lubricating grease, the highmolecular weight portion of the total soap content is complexed with alow molecular weight acid salt. Such low molecular weight acids includethose having from about 1 to about 6 carbon atoms, such as formic,acetic, propionic, and similar acids, including their hydroxyderivatives such as lactic acid, etc. The

, amount of the low molecular weight acid salt that is used to form thecomplex with the high molecular weight fatty acid will again depend uponthe use for which the grease composition is desired. It has recentlybeen found that grease compositions containing a high ratio of lowmolecular weight acid to high molecular weight acid are particularlyoutstanding for high temperature use. Especially desirable greasecompositions may be prepared by thickening to a grease consistency alubricating oil with a complex alkaline earth soap grease wherein thecomplex soap comprises a mixture of high molecular weight acid salt in amol ratio of salt to soap of between about 7.5:1 to 50:1, preferably 9:1to 15:1.

The total amount of the soap used in preparing the grease formulationswill vary from between about 3 to about 30 weight based on the weight ofthe total composition. Within this broad range, from about 6% to about20% will normally be found to be preferable. The choice of themenstruurn used in preparing the lubricating greases of invention may bemade from a wide range of lubricating oils, whether naturally occurringor synthetic. Quite generally this oil should have a viscosity withinthe range of about 35 to about 200 SUS at 210 F. and flash points ofabout 350 to about 600 F. Among the synthetic lubricants operable may bementioned diesters of dibasic acids, complex esters, formals,hydrocarbon polymers, silicone oils, polyglycol derivatives, etc. Thenaturally occurring lubricating oils used 6 may be either of naphthenicor paraflinic origin refined by any of the techniques well known to theart.

When it is desired to utilize the formals of the hydroxy fatty acids inconjunction with another high molecular weight fatty acid, the two soapforming materials may be admixed in any desired proportion. In otherwords, the soap may consist entirely of the metallic soap of the formalof the hydroxy fatty acid, or relatively minor amounts, that is fromabout 1% to about 10%, of the total high molecular weight acid.

Any of the commonly known grease additive materials such as stabilizers,oxidation inhibitors, cooling agents, tackiness agents or the like maybe blended with the grease compositions of this invention.

To summarize briefly, the instant invention relates to new and improvedlubricating grease compositions which are prepared by thickening alubricating oil base stock to a grease consistency with a minor butgrease forming amount of a metal soap of a formal of a hydroxy fattyacid. The hydroxy fatty acid may be a mono hydroxy material or it may bea polyhydroxy fatty acid. Other grease making fatty acid soaps may becombined with the formals and the total grease making soap composiionmay be complexed with low molecular weight acids such as formic acid,acetic acid, furoic acid and the like. Normally from 5% to 30% by weightof the total grease thickener will be used, preferably about 6 weightpercent to about 20 weight percent. When a complex grease composition iscontemplated, the low molecular Weight acid used to form the complex maybe present in amounts varying between about 3 to about 20 weight percentof the total composition. Especially preferred are the complex greasecompositions comprising a low molecular weight acid having from 1 to 6carbon atoms with high molecular weight acids having from 12 to 30carbon atoms in a mol ratio of low molecular weight acid to highmolecular weight acid of from 7.5 :1 to 20:1.

What is claimed is:

1. A lubricating grease composition comprising a mineral lubricating oilcontaining combined therein a minor, but grease thickening, amount ofmetal soap of a formal of a hydroxy-fatty acid having from about 14 to22 carbon atoms, said metal constituent being selected from the groupconsisting of alkali and alkaline earth metals.

2. A lubricating grease composition which comprises alubricating oilbase stock thickened to a grease consistency with a complex soap whichcomprises a metal salt of a low molecular weight acid, a metal soap of ahigh molecular weight fatty acid and a metal soap of a formal of ahydroxy-stearic acid, said metal constituents being selected from thegroup consisting of alkali and alkaline earth metals.

3. A lubricating grease composition according to claim 2 wherein saidmetal soap and wherein said metal salt are of calcium.

4. A lubricating grease composition according to claim 2 wherein saidhydroxy-stearic acid is a mono-hydroxystearic acid.

5. A lubricating grease composition according to claim 2 wherein saidhydroxy-stearic acid contains more than one hydroxy group.

6. A lubricating grease composition comprising a major proportion of alubricating oil and a minor, but grease thickening, amount of asoap-salt complex which comprises the alkaline earth metal soap of amixture of a high molecular weight fatty acid and a formal of ahydroxy-stearic acid and the alkaline earth metal salt of a lowmolecular weight acid containing from 2 to 6 carbon atoms, the molarratio of said salt to said mixture of soaps in said complex beingbetween about 7.5 :1 to 20:1, and wherein said mixture consists of aboutequal weight percentages of said high molecular weight fatty acid andsaid formal.

7. A lubricating grease composition comprising a lubricating oilthickened to a grease consistency with a metal .7 2,850,456 a t 7 V a ssoap-salt complex, which consists of ametal salt of a 9- The lubri ggrease Composition of claim 7 low molecular weight fatty acid anda-metal soap of a wherein Said Y Y fatty acid Y O Y Stearic formal ofahydroxy fatty acid having from about 14 a id. a

to 22 carbon atoms, said metal constituents being selected Q p f thegroup consisting f alkali and alkaline earth 5 References Cited-1n thefile of H118 patent metals and wherein the molar ratio of said salt tosaid UNITED STATES PATENTS soap is about 7.5 :1 to 20:1.

8. The lubricating grease composition of claim 7 2,397,956 Fraser P7,1946

wherein said metal salt is acetic acid.

1. A LUBRICATING GREASE COMPOSITION COMPRISING A MINERAL LUBRICATING OILCONTAINING COMBINED THEREIN A MINOR, BUT GREASE THICKENING, AN AMOUNT OFMETAL SOAP OF A FORMAL OF A HYDROXY-FATTY ACID HAVING FROM ABOUT 14 TO22 CARBON ATOMS, SAID METAL CONSTITUENT BEING SELECTED FROM THE GROUPCONSISTING OF ALKALI AND ALKALINE EARTH METALS.